N = int(input())
s = input()
r = s.count("R")
print(s[:r].count("W")) N = int(input()) N int(input()) int input() input s = input() s input() input r = s.count("R") r s.count("R") s.count s count "R" print(s[:r].count("W")) print s[:r].count("W") [:r].count [:r] s :r r count "W" s = input() input() s r = s.count("R") s.count("R") r N = int(input()) int(input()) N
N = int(input())
s = input()
r = s.count("R")
print(s[:r].count("W"))